The Jamaican Quassia or Bitterwood, Picrasma excelsa is a member of the plant family Simaroubaceae in the order Sapindales. It is a tree, 6-25 meters tall, native to the Greater Antilles of the West Indies, and is common in various localities in Jamaica. See, Adams, C. D. Flowering Plants of Jamaica. 1972. University Press, Glasgow, p. 390. Other members of this family include for example, Quassia amara, Picrasma quassioides, and Quassia africana 
Quassin and neoquassin (FIGS. 1 and 2), are used in alcoholic beverages, e.g. aperitifs such as Campari™, and other beverages and grapefruit flavoured drinks, such as Ting™. See for example, Coyle, L. P. The World Encyclopedia of Foods. Facts On File, Inc., New York, 1982, p. 543.
Quassin and neoquassin have been reported to stimulate the appetite and to aid digestion; and because of these properties they are ingredients of aperitifs, and are also used in the treatment of the eating disorder, anorexia nervosa. See for example, Bown, D. The Royal Horticultural Society Encyclopedia of Herbs and Their Uses, 1995, Dorling Kindersley, London, p. 327; and Chavalier, A. The Dorling Kindersley Encyclopedia of Herbal Medicine. 2000. Dorling Kindersley, p. 247.
Quassinoids have also been indicated in the use of medicaments due to biological activity such as anti-malarial, anti-insecticidal, anti-amoebicidal, anti-leukemic, and anti-viral properties. See for example, U.S. Pat. No. 5,639,712 to Grieco et al.
Jamaica has been an important source of quassin and neoquassin, and traditionally, dried wood chips of P. excelsa have been exported; and from these a mixture of quassin and neoquassin has been extracted overseas. Data from the Statistical Institute of Jamaica (STATIN) show that approximately 119 tons of wood chips were exported in 2001 at a value of approx. J$7M. See for example, FIG. 3 from The Statistical Institute of Jamaica, STATIN.
There is a need for a process that will produce quassinoids such as quassin and/or neoquassin in crystalline form, as this would afford the marketing of a purified end product. The development of such a process would also lead to the possibility of local processing with the economic benefits of exporting a value added product, providing local employment, etc.
The quassin/neoquassin content of the wood of Picrasma excelsa, Jamaican Quassia, and of Quassia amara, Surinam Quassia, has recently been quantified analytically by UV spectrophometry and by analytical HPLC. See for example, Villalobos, R; Marmillod, D; Ocampo, R; Mora, G; Rojas, C. Acta Hort (ISHS), 1999, 502, 369-376. Variations in the quassin and neoquassin content in Quassia amara (Simaroubaceae) in Costa Rica: Ecological and management implications. Also see Nestler, T; Tittel, G; Wagner, H. Planta Med. 1980.38, 204-213. Quantitative estimation of bitter quassinoids in Quassia amara and Picrasma excelsa; and Sugimoto, N; Sato, K; Yamakaki, T; Tanamoto, K. Shokuhin Eiseigaku Sasshi. 2003. 44, 328-331. Analysis of constituents in Jamaican quassia extract, a natural bittering agent.
The percentages of total bitter substances are reported to range from 0.14 to 0.28%. In P. excelsa, quassin and neoquassin were detected in equal quantities, 0.09% each, and these were found to comprise the total bitter substances in this wood (0.18%). The isolation of quassin/neoquassin from wood of Q. amara and P. excelsa described by Clark results in yields of 0.15 to 0.18%, and 0.1% respectively. See for example, Clarke, E. P. J. Am. Chem. Soc. 1937. 59, 927-931. The preparation and purification of quassin and neoquassin, with information concerning their molecular formulas; and Clarke, E. P. J. Am. Chem. Soc. 1938. 60, 1146-1148. Quassin III. Picrasmin. The same process is used for the wood of both species. This entails extraction of the wood with hot water, treatment of the aqueous extract with lead acetate and carbon, trituration of the resulting solid with chloroform, evaporation of the chloroform and finally crystallization of the quassinoid mixture from aqueous methanol. The British Pharmaceutical Codex (BPC) method of 1911 requires extraction of P. excelsa wood with 50% alcohol, neutralization of the extract with MgO, acidification with tartaric acid followed by evaporation of the alcohol and extraction of the residue with chloroform; the crystalline quassinoids are obtained from the chloroform extract by removal of the solvent and crystallization from alcohol-diethyl ether mixtures. No yields are reported for this BPC method. See for example, British Pharmaceutical Codex. The Pharmaceutical Press: London, 1911. Quassinum.
The BPC of 1949 describes only a method for preparation of an aqueous crude extract of quassia based on cold percolation with water; subsequent codices do not provide isolation methods for quassin-neoquassin. See for example, British Pharmaceutical Codex. The Pharmaceutical Press: London, 1949: p 1129, Extractum Quassiae; and British Pharmaceutical Codex. The Pharmaceutical Press: London, 1973, p 422. Quassia.
All preparative scale isolation methods leading to clean mixtures of quassin/neoquassin described thus far, entail the use of one or more of the toxic, or carcinogenic or otherwise hazardous, or banned substances: lead acetate, chloroform, methanol, diethyl ether. There therefore continues to be a need for an isolation method that does not require the use of such substances.